[Users] TwoPunctures::Newton_maxit

[Yosef Zlochower]

I think the idea is that one typically wants the solution to be nearly
as accurate as possible, i.e., with the tolerance set to the round-off
limit. Often, this means setting tol lower than the unknown
round-off limit and having the system harmlessly  iterate a few times at 
the round-off level. Choosing a reasonable tol and maxit usually
leads to the desired behavior (i.e., if round off is larger than tol, 
the solve will still complete reasonably fast, and if round off is less 
than tol, the solve finishes before maxit is reached).


I have also hit the issue where the solve failed entirely and I didn't 
catch it. Perhaps a tolerance interval a better solution.

for i range(maxit)
    NewtonIteration
    break if err < tol_min

abort if err > tol_max



On 09/14/2016 07:24 AM, Ian Hinder wrote:
> Hi,
>
> What is the logic behind the parameter TwoPunctures::Newton_maxit?  Its
> default is set to 5, and if the Newton iteration doesn't converge in
> this number of iterations, the solution is just used anyway.  Shouldn't
> there be a fatal error in this case?  Is it ever legitimate to use a
> solution which has not converged to within the tolerance?  I think I
> would prefer to be told to specify a larger tolerance than to have a
> solution which does not meet the tolerance I set.
>
> --
> Ian Hinder
> http://members.aei.mpg.de/ianhin
>
>
>
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